The present invention relates to grinding and shredding systems and, more particularly, to grinding and shredding systems which include a rotary auger screw.
A typical shredding device is shown in Koenig U.S. Pat. No. 4,993,649 and includes a housing having a front wall, a rear bulkhead which is part of a motor enclosure, side walls and an open top which acts as an infeed hopper. The bottom of the housing includes a floor which is partially conical in shape and which includes a pair of sliding doors that are positionable between fully-opened and fully-closed positions. A pair of opposing, tapered auger screws are mounted rotatably within the housing and are driven by hydraulic motors enclosed within the equipment enclosure.
The screws are oppositely oriented and have axes of rotation oriented substantially horizontally and parallel to each other. The screws are driven to counter-rotate within the housing and interact to crush, grind and shred material. The size reduction effected by the auger screws is enhanced by providing the screws with teeth which project radially from the outer peripheries of the screw flights, and stationary breaker bars mounted on the conical portions of the floor. The meshing of the teeth and breaker bars provides a shearing action which further reduces particle size.
The maximum hopper opening size of such a dual auger machine is limited by the size of the auger screws within the housing. With each geometry of auger screw, there is an optimal spacing between screw flights. If such spacing is exceeded, the cooperation of the screws to reduce particle size is reduced.
However, there is a need for providing a large scale device or system which is capable of receiving, holding and processing large volumes of waste material at relatively rapid rates. It is not practical to provide a plurality of discrete dual auger units such as that disclosed in the Koenig U.S. Pat. No. 4,993,649. Accordingly, there is a need for a unitary system which has a relatively high throughput capacity, yet is efficient in reducing particle size.